This invention relates to a signal recording and/or reproducing apparatus, and is suitably applied to a video tape recorder for recording and/or reproducing, for example, character information multiplexed with a television broadcasting signal.
Conventionally, in a character multiplexed broadcasting in which character information is transmitted by multiplexing it with a television broadcasting signal, a character signal constituted of characters is inserted into a horizontal scan period (10-21 h) within a vertical blanking period as a digital signal and transmitted (FIG. 1(A)).
Here, the character signal is transmitted as a data line composed of 296 bits per one horizontal scan period and the data line is constituted with a synchronizing portion of 24 bits and a data packet of 272 bits.
The data packet is constituted with a prefix (PFX) of 14 bits for controlling the multiplex transmission, a data block of 176 bits and a check code of 82 bits (FIG. 1(B)) and a plurality of such data blocks form a data group (FIG. 1(C)).
Here, a head of the data group is constituted with a data group header for identification and control of the data group and comprises a data group identification signal (DGI), a data group retransmission signal (DGR), a data group link code (DGL), a data group serial number (DGC), a data group size (DGS) and operation data, in that order (FIG. 2).
A plurality of such data groups form a program data and a program management data is transmitted by No. 0 data group among respective data groups and a first page data through Nth page data are transmitted by a first through Nth data groups.
Incidentally, in order to receive a character multiplexed broadcasting at high quality (bit error is not more than 0.005 and eye opening rate is not smaller than 50%) and to record or reproduce on a magnetic tape by using a video tape recorder, it is necessary to make a band characteristics to have not more than -3 [db] at 3.58 [MHz] and to make a group delay characteristics flat at not higher than 3 [MHz].
Previously, there was a problem that, in a case where a character multiplex broadcasting having a band in the order of 5.72 [MHz] is recorded or reproduced by a video tape recorder, particularly, in reproducing, it is difficult to realize this condition and a demodulation in recording or reproducing a character multiplex broadcasting by means of a video tape recorder is difficult.